Hematopoiesis in the fetal liver is impaired by targeted mutagenesis of a gene encoding a non-DNA binding subunit of the transcription factor, polyomavirus enhancer binding protein 2/core binding factor

The Pebpb2 gene encodes a non-DNA binding subunit of the heterodimeric transcription factor, polyomavirus enhancer binding protein 2/core binding factor (PEBP2/CBF), and is rearranged in inversion of chromosome 16 associated with human acute myeloid leukemia. To investigate its physiological function, Pebpb2 was mutated by a targeting strategy to generate a null mutant. The homozygous mutation in mice proved lethal in embryos around embryonic day 12.5, apparently due to massive hemorrhaging in the central nervous system. In addition, definitive hematopoiesis in the liver was severely impaired. The observed phenotype was indistinguishable from that reported for homozygous disruption of AML1, which encodes a DNA binding subunit of PEBP2/CBF. Thus, the results indicate that the two subunits function together as a heterodimeric PEBP2/CBF in vivo and that PEBP2/CBF plays an essential role in the development of definitive hematopoiesis.

[Successful combination chemotherapy for a post-operative gastric cancer patient with multiple liver metastases and elevated CEA]

A 75-year-old male was admitted one year after surgery for advanced gastric cancer. He was diagnosed as having multiple liver metastases with elevated serum CEA level. Combination chemotherapy consisting of THP-ADM, MMC and 5'-DFUR was done in the outpatient clinic. As a result, both multiple metastatic liver tumors and serum CEA level showed a remarkable response.

[Measurement of the plasma transforming growth factor-beta 1 (TGF-beta 1) level in patients of gastric carcinoma--compared with the serum IAP level and the lymphocyte subsets (CD3, CD4, CD8)]

We evaluated the clinical significance of the plasma TGF-beta 1 by enzyme-linked immunosorbent assay (ELISA) in 40 patients with gastric carcinoma before operation who were hospitalized at our department between August 1992 and March 1993. Moreover, we examined the correlation of the immunosuppressive acidic protein (IAP) in the serum with the plasma TGF-beta 1 level. The lymphocyte subsets were analyzed with monoclonal antibodies (CD3, CD4, CD8) and compared with the plasma TGF-beta 1 level. Results 1) The plasma TGF-beta 1 was significantly high in patients with advanced stage of gastric carcinoma (with respect to the depth invasion) and poorly differentiated adenocarcinoma (histological type) (p < 0.01). When the carcinoma was macroscopically found to be advanced, TGF-beta 1 was higher in the invasive type than in the noninvasive type (p < 0.05). 2) We found a significant correlation between the plasma TGF-beta 1 and IAP in the serum (n = 25, r = 0.677, p < 0.01). 3) The lymphocyte fraction of CD3, CD4 was decreased in patients with a high level of TGF-beta 1, and was related with the plasma TGF-beta 1 level. Thus, TGF-beta 1 was presumed to be deeply associated with in the growth and progression of gastric carcinoma and related to systemic immunosuppressive reaction.

Expression of the Runt domain-encoding PEBP2 alpha genes in T cells during thymic development

The PEBP2 alpha A and PEBP2 alpha B genes encode the DNA-binding subunit of a murine transcription factor, PEBP2, which is implicated as a T-cell-specific transcriptional regulator. These two related genes share the evolutionarily conserved region encoding the Runt domain. PEBP2 alpha B is the murine counterpart of human AML1, which is located at the breakpoints of the 8;21 and 3;21 chromosome translocations associated with acute myeloid leukemia. Northern (RNA) blots of various adult mouse tissues revealed that the levels of expression of both genes were most prominent in the thymus. Furthermore, transcripts of PEBP2 alpha A and mouse AML1/PEBP2 alpha B were detected in T lymphocytes in the thymuses from day 16 embryos and newborns, as well as 4-week-old adult mice, by in situ hybridization. The expression of the genes persisted in peripheral lymph nodes of adult mice. The transcripts were detected in all the CD4- CD8-, CD4+ CD8+, CD4+ CD8-, and CD4- CD8+ cell populations. The results indicated that both genes are expressed in T cells throughout their development, supporting the notion that PEBP2 is a T-cell-specific transcription factor. Transcripts of mouse AML1/PEBP2 alpha B were also detected in day 12 fetal hematopoietic liver and in the bone marrow cells of newborn mice. The implication of mouse AML1/PEBP2 alpha B expression in hematopoietic cells other than those of T-cell lineage is discussed in relation to myeloid leukemogenesis.

[Successful neoadjuvant chemotherapy in a patient with advanced gastric cancer with multiple liver metastases]

We described a case of advanced gastric cancer with multiple liver metastases, who was placed on neoadjuvant chemotherapy using CDDP and 5-FU (FP therapy) with a marked reduction in tumor load. The case was a 67-year-old male, who was admitted with a Borrmann III type advanced gastric cancer with multiple liver metastases. FP chemotherapy was carried out two times as neoadjuvant chemotherapy. As a result, both primary cancer and the metastatic tumors showed a remarkable reduction. Then, total gastrectomy with combined resections of spleen and transverse colon was done, and a reservoir was inserted into the hepatic artery. Postoperatively, intrahepatic arterial infusion of CDDP with oral administration of 5-FU was done in the outpatient clinic for about eleven months. But thirteen months later, he died from the rapid recurrence of the tumor.

Multistep regulation of enhancer activity of the 21-base-pair element of human T-cell leukemia virus type I

We examined the regulatory mechanisms of binding and transcriptional enhancement of the 21-bp core element of the enhancer of human T-cell leukemia virus type I (HTLV-I) in response to forskolin, 12-O-tetradecanoylphorbol-13-acetate (TPA), and a viral transactivator, p40tax. The 21-bp core element has been shown to bind to a cyclic AMP-responsive element binding protein (CREB)-like molecule at the site of an imperfect palindrome containing the TGAC motif. Experiments with oligonucleotides with mutations in the imperfect palindrome demonstrated that one TGAC motif is necessary and sufficient for both the binding of the CREB-related factor and transcriptional activity in response to forskolin in a human T-cell line, Jurkat. We also found that binding of the CREB-like factor to the 21-bp core element was enhanced by treatment with TPA, with little effect on transcriptional activity; in contrast, forskolin and p40tax did not facilitate binding, though they enhanced transcription. The combination of forskolin and TPA synergistically induced the transcription activity of the element, showing a hierarchical mechanism of regulation of the HTLV-I core enhancer element to levels sufficient for formation of the factor-enhancer complex and for activation of the complex. Added to those findings, our results indicate that the modes of activation by forskolin and p40tax are different from each other.

Synergism between two distinct elements of the HTLV-I enhancer during activation by the trans-activator of HTLV-I

We have conducted functional studies of the enhancer elements of human T-cell leukemia virus type I (HTLV-I) using the human T-cell lines Jurkat and MOLT 4, which are negative for HTLV-I, and MT-2 and TL-Mor, which carry the proviral genome of HTLV-I. Two distinct elements have been implicated in function of the HTLV-I enhancer. One is the 21-base-pair (bp) core element that is responsible for trans-activation by the HTLV-I trans-activator p40tax and that has the ability to bind to cyclic-AMP responsive element binding factor (CREB)-like factor(s). The other is a region interposed between the 21-bp elements. In this study we demonstrate that a subfragment (C26) in the region between the 21-bp elements is involved in trans-activation by p40tax, possibly through binding to an NF-kappa B-like nuclear factor or factors. Formation of the protein-DNA complex with the C26 subfragment was positively affected by p40tax. The C26 element conferred partial responsiveness to p40tax when linked to one copy of the 21-bp element that, by itself, showed little activation in response to p40tax. However, the C26 element alone, even when repeated, could not be activated by p40tax, unlike other NF-kappa B-binding elements. In contrast, the C26 element itself was profoundly activated upon stimulation with 12-O-tetradecanoylphorbol-13-acetate. These findings therefore suggest that the HTLV-I enhancer contains multiple functional elements, including binding sites for at least CREB- and NF-kappa B-like factors, which synergistically cooperate in activation of the HTLV-I enhancer in response to p40tax. Our results also demonstrate that TPA-dependent activation of the HTLV-I enhancer may be mediated through the C26 element.

Review of pancreatic cancer

In 83 cases of pancreatic cancer (25 resected and 58 non-resected cases) which underwent laparotomy in the Department of General and Gastroenterological Surgery, Osaka Medical College Hospital over the past 11 years, we analyzed symptoms at diagnosis, duration of illness, tumor markers, surgical procedures, and long-term results. In many cases, jaundice was the premonitory symptom of pancreatic cancer. There was no relationship between duration of illness and tumor resectability. In analysis of tumor markers, abnormal CA19-9 levels were noted in 71% of resected cases and 89% of non-resected cases, and abnormal CEA, elastase and amylase levels were found in 38, 46 and 47% of resected cases and 76, 58 and 27% of non-resected cases, respectively. Operative mortality was higher for non-resected cases (22%) than that for resected cases (8%). Long-term results were significantly better in resected cases than non-resected cases. However, 1-, 2- and 3-year survival rates after macroscopic curative resection were 45, 19 and 9%, respectively. Prognosis of patients after absolute non-curative resection was poor, indicating no efficacy of the resection. To improve these very poor surgical results for pancreatic cancer, the early cancer detection and multi-disciplinary therapy seem to be necessary.

Cell line-dependent response of the enhancer element of simian virus 40 to transactivator p40tax encoded by human T-cell leukemia virus type I

The trans-acting transcriptional factor p40tax of human T-cell leukemia virus type I (HTLV-I) can activate expression not only of its own viral genes but also of other viral and cellular genes. We examined the cis-acting sequences in the simian virus 40 (SV40) enhancer required for its activation by HTLV-I p40tax. Experiments with chloramphenicol acetyltransferase constructs bearing the SV40 enhancer elements revealed that p40tax-dependent transactivation of the SV40 enhancer is mediated through the C element that contains the typical sequence for binding of a nuclear factor NF-kappa B. Activation of the C element by p40tax was seen in a limited set of cell lines as was also seen with the whole enhancer of SV40. Binding of NF-kappa B or NF-kappa B-like factor to the SV40 C element increased when p40tax was expressed. The fact that HTLV-I p40tax utilizes a cellular regulatory mechanism to transactivate the SV40 enhancer in a cell-dependent manner may have implications for the pathogenesis of adult T-cell leukemia.

[Experimental studies on haematogenous osteomyelitis due to Staphylococcus hyicus in mice]

10(7) colony forming units of 18 different strains of Staphylococcus hyicus were intravenously administered into mice. Five mice as a group received each strain of S. hyicus. At 14 days after inoculation, 11 out of 18 strains were found in the bone marrow. Out of these 11 strains, SMUH 10 and SMUH 18 caused remarkable inflammation which was characterized by roentgenographical change. A number of these organisms were detected in the bone marrow until 28 and 42 days after the injection, suggesting specific lodgement of the strain in mouse bone marrow. X-rays of the upper and lower extremities taken 14 days after inoculation showed multiple small radiolucent areas surrounded by small rims representing osteosclerosis. However, these changes did not show any aggravation during 70 days after inoculation suggesting tendency of improvement.

Differential activation of the 21-base-pair enhancer element of human T-cell leukemia virus type I by its own trans-activator and cyclic AMP

A transcriptional trans-acting factor p40tax of human T-cell leukemia virus type I (HTLV-I) functions as an inducer for expression of HTLV-I provirus via activation of the enhancer in the long terminal repeat of HTLV-I. In addition to p40tax and a tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, we report here that forskolin, an activator of adenyl cyclase, also induces function of the HTLV-I enhancer. Experiments with mutants of the HTLV-I enhancer revealed that TPA-induced activation was not mediated by solely a 21-base-pair (bp) sequence that is repeated three times in the enhancer, whereas the 21-bp enhancer element can act as a sufficient cis-acting sequence for activation by both p40tax and forskolin. In addition, we found that nuclear factor(s) like the cyclic AMP-responsive element (CRE) binding factor could bind to the HTLV-I 21-bp enhancer element. However, a difference was found in sequences required for activation by p40tax and forskolin. A CRE related sequence present in the 21-bp enhancer element was enough for forskolin-induced activation. On the other hand, p40tax required a much longer sequence that is overlapping but not identical to the CRE related sequence, suggesting that the forskolin-induced cyclic AMP pathway may be partly involved in, but not sufficient for p40tax-mediating trans-activation of the HTLV-I enhancer.